10 Doctor Who Characters Who Can Never Die

The Sisterhood of Karn is one of the Whoniverse's most mysterious collectives. We haven't spent much time with this all-female group of Gallifreyans, and its ultimate purpose has never been made crystal clear.

But what is crystal clear is that the Sisterhood is incredibly powerful, as evidenced by its use of a rather strong brew called The Elixir of Life, which can not only heal injuries, but can make the drinker immortal.

Both the Sisterhood and the Elixir were introduced in the Fourth Doctor serial The Brain of Morbius, where that potent potion was used to prevent the Doctor from dying. The Night of the Doctor then saw the Sisterhood bring the Eighth Doctor back to life after a fatal spaceship crash, before using a special version of the Elixir to trigger his regeneration into the War Doctor.

The Sisterhood also regularly uses the Elixir for itself. It grants them extended life whenever they drink it, so, basically, they have immortality juice on tap, which must come in handy in a universe with deadly aliens around every street corner.